A snap gauge is a form of go/no go gauge. It is a limit gauge with permanently or temporarily fixed measurement aperture which is used to quickly verify whether an outside dimension of a part matches a preset dimension or falls within predefined tolerances.

Snap gages are among the oldest and simplest measuring instruments. They are used to measure the outside diameter of round parts such as shafts and the thickness of many other components. The first type snap gages were fixed limit gages which only confirmed the part being measured was within its size limits.

Single Ended, Double Snap Gauges